Process for producing elastic filaments and bristles

ABSTRACT

THE INVENTION COMPRISES FILAMENTS AND BRISTLES HAVING A BASIS OF A DIORGANOPOLYSILOXANE WHICH COMBINE A KILOMETRIC BREAKING STRENGTH ABOVE 1.25 WITH AN ELONGATION AT BREAK OF AT LEAST 300%. THEY ARE MADE FROM DIORGANOPOLYSILOXANES IN WHICH AT LEAST 60% OF THE ORGANIC SUBSTITUENT GROUPS ARE METHYL AND A SMALL PROPORTION (0.32%) ARE VINYL, BY EXTRUSION FOLLOWED BY STRETCHING, A HEAT TREATMENT TO &#34;VULCANIZE&#34; THE PRODUCTS, A FURTHER STRETCH AND PREFERABLY A FURTHER HEAT TREATMENT. THE PRODUCTS MAY ALSO BE GIVEN A THIRD HEAT TREATMENT WHILE WOUND UP ON A SUPPORT. THE COMPOSITION WHICH IS EXTRUDED CONTAINS, BESIDES THE DIORGANOPOLYSILOXANE, A FILLER, A CROSSLINKING CATALYST, PREFERABLY OF THE FREE RADICAL TYPE, AND OPTIONALLY A PLASTICIZER, ESPECIALLY AN ORGANISICON COMPOUND.

Dec. 25, 1973 p COUCHOUD ET AL I 3,781,490

PRE'CESS FOR PRODUCING ELASTIC FILAMENTS AND BRISTLES Original. Filed Dec. 24, 1969 INVENTORS PAUL COUCHOUD, VINCENT ROCHINA ATTORNEYS UnitedStates Patent 3,781,400 PROCESS FOR PRODUCING ELASTIC FILAMENTS AND BRISTLES Paul Couchoud and Vincent Rochina, Lyons, France, assignors to Societe Rhodiaceta, Paris, France Original application Dec. 24, 1969, Ser. No. 887,987, now

abandoned. Divided and this application Sept. 28,1971,

Ser. No. 184,631

Int. Cl. D01d 5/12 US. Cl. 264-410 F 11 Claims ABSTRACT OF THE DISCLOSURE The invention comprises filaments and bristles having a basis of a diorganopolysiloxane which combine a kilometric breaking strength above 1.25 with an elongation at break of at least 300%. They are made from diorganopolysiloxanes in which at least 60% of the organic substituent groups are methyl and a small proportion (0.3- 2%) are vinyl, by extrusion followed by stretching, a heat treatment to vulcanize the products, a further stretch and preferably a further heat treatment. The products may also be given a third heat treatment while wound up on a support. The composition which is extruded contains, besides the diorganopolysiloxane, a filler, a crosslinking catalyst, preferably of the free radical type, and optionally a plasticizer, especially an organisilicon compound.

This is a division of application Ser. No. 887,987, filed Dec. 24, 1969, and now abandoned.

The invention relates to new elastic filaments and bristles based on vulcanized diorganopolysiloxanes which have an improved tenacity, and to their production.

By diorganopolysiloxanes are meant compounds of high molecular weight consisting of structural units of formula:

i. l -S1O- Li. J in which R and R are the same or different monovalent organic radicals.

It is already known to make elastic filaments or films based on diarylpolysiloxanes from solutions of the polymers in organic solvents for example chloroform or toluene. The filaments or films so obtained have a satisfactory elasticity but a mediocre tensile strength, generally of the order of 30 to 60 kg./cm. It is known that the tensile strength of these filaments or films can be improved by subjecting them to a heat treatment at 200 C. for about 2 hours. This heat treatment makes it possible to obtain tensile strengths of almost 100 kg./cm. but also results in a very great reduction in the elongation at break.

It is furthermore known to make elastic filaments based on a vulcanized diorganopolysiloxane by extruding, through an orifice of any desired diameter, at ordinary temperature, a composition comprising (a) a diorganopolysiloxane in which the structural units have the formula:

in which R is a methyl, phenyl or trimethylsilylmethyl radical, with at least 90% of the radicals R being methyl,

(b) a silica filler in amount 20 to 50% on the weight of the diorganopolysiloxane, and

(c) a vulcanization catalyst of the peroxide type, and subjecting the filament thus obtained to a heat treatment, for example by passing it through a tube heated to about 350 C.

Filaments obtained in this way have a satisfactory elongation at break, of the order of 600%, but their tensile strength is still relatively low, less than kg./cm. this being a value which in the case of the composition described essentially corresponds to a kilometric breaking strength of 1. The tensile strength of these filaments, which is significantly less than that of filaments of natural rubber, makes them too delicate for general use in the textile field.

In one aspect the present invention consists in new filaments and bristles based on a vulcanized diorganopolysiloxane which possess both a kilometric breaking strength above 1.25 and an elongation at break of at least 300%.

Preferably the diorganopolysiloxane is one which, in its unvulcanized state has the formula:

in which the symbols R represent monovalent unsubstituted or substituted hydrocarbon radicals, of which at least 60% are methyl and 0.03-2% are vinyl, and which are free from substituents that could interfere with the vulcanization of diorganopolysiloxane or affect the longterm stability of the filaments and bristles, the symbols R and R which may have the same or different meanings, represent hydrogen or an SiR group, and n represents a number from 2,000 to 20,000.

The invention consists also in a process for obtaining these filaments and bristles, which comprises extruding through a spinneret at ordinary temperature, a composition consisting essentially of (a) 1000 parts by weight of an unvulcauized diorganopolysiloxane of the above formula,

(b) 300 to 1000 parts by weight of a filler, and

-(c)' 3 to 30 parts by weight of a vulcanization catalyst for the diorganopolysiloxane, stretching the resulting filaments or bristles at an ordinary temperature at a stretch ratio between 1 and 1.5, heating the filaments or bristles to a temperature of -320 C. for 0.1 seconds to 5 minutes, all without allowing them to make frictional contact with any solid object in advance of the heating means, giving the filaments or bristles a second stretch at an ordinary temperature at a stretch ratio of 1.2-4, and winding them up at a speed such that the overall stretching ratio is from 12-4.

(Although in the first stretch the stretch ratio may be 1, so that there is no actual increase in the length of the extruded filament or bristle, the latter is still kept under a degree of tension which justifies the use of the word stretch.)

The diorganopolysiloxane can terminate, at each end of its chain, in a hydroxyl grgoup or a triorganosiloxyl group, or have a triorganosiloxyl group at one end and a hydroxyl group at the other. Preferably, a diorganopolysiloxane in which the value of n and the nature of the radicals R are such that the viscosity is between 10,000 and 600,000 poises at 25 C. is used. The radicals R can be chosen from alkyl radicals having 1 to 3 carbon atoms such as methyl, ethyl or propyl; alkyl radicals substituted by halogen atoms or by a nitrile group such as 3,3,3-tri- Ifluoropropyl, p-cyanethyl or 'y-cyanopropyl; the vinyl radical; the 2,2-difluoro-cyclopropyl radical and the phenyl radical, which may or may not be substituted by halogen; the proportion of vinyl radicals can vary within the limits of 0.03 and 2%. The preparation of these diorganopolysiloxanes is described in various patents, for example French Pats. Nos. 1,132,048, 1,329,088, 1,382,- 285, 1,561,922 and 1,451,269.

As a vulcanization catalyst, it is possible to use known free radical-producing compounds, for example organic per compounds such as 2,4-dichlorobenzoyl peroxide, dicumyl peroxide, t-butylisopropyl percarbonate, benzoyl peroxide, t-butyl perbenzoate, di-t-butyl peroxide, O-O-tbutyl percarbonate and O-isopropyl percarbonate, and the oxaziridines; it is also possible to use catalysts based on platinum, in particular mixtures of a hydrogenopolysiloxane and platinum, or compounds such as those described in French Pat. No. 1,384,429 or 1,524,288.

Pyrogenic silicas and silicas produced by precipitation, having a high specific surface area, which may or may not have been treated with an organosilicon compound, can be used as fillers, as also can other forms of silica such as diatomaceous silicas and ground quartz, talc, mica, clay, sand, lampblack, graphite, oxides of titanium, iron magnesium, zinc, antimony and aluminium, and carbonates of calcium, magnesium and zinc. Also fibrous fillers such as asbestos or glass fibre can be used, as can metallic powder such as those based on aluminium, tin, zinc or iron. Other filler or adjuvants can also be incorporated such as organic or inorganic pigments, phthalocyanins, inorganic, semi-organic or organic polymers such as carboranes, phosphonitrile chlorides, polytetrafluorethylene, polychlorotrifiuorethylene, polyvinyl chloride, polybenzimidazoles, polyimides, thixotropic products such as the triglycerides of long-chain aliphatic carboxylic acids, agents which filter sunlight, oxidation inhibitors and dielectric materials.

These fillers and adjuvants can be incorporated in the compositions of the invention in amounts which can range up to 1,000 parts per 1,000 parts of the diorganopolysiloxane.

To prevent the compositions curing during storage, it is desirable to add to them one or more known organosilicon compounds which play the role of a plasticizer; examples of such compounds include (tetramethylethylenedioxy) dimethylsilane, diphenylsilanediol, and hydroxylated or alkoxylated oils; other compounds which can be used are described in French Pats. Nos. 1,111,969 and 1,161,094 and in US. Pat. No. 2,890,188.

The amount of plasticizer used will generally not exceed 50 parts by weight per 1,000 parts of diorganopolysiloxane.

To extrude this composition, a screw extruder or any other extrusion device can be used, the only necessary condition obviously being that a regular feed to the spinneret should be obtained. The spinneret may comprise one or more orifices of various shapes and sizes.

The first stretching is preferably carried out in the zone located in the immediate vicinity of the spinneret. The ratio of this first stretching, that is to say the ratio of the linear speed at which the filaments or bristles are forwarded by the first stretching device to the linear extrusion speed must be between 1 and 1.5.

In the zone between the spinneret and the area where the heat treatment starts, the filaments or bristles, which are still fragile, must not be subjected to any friction or contact with any element of the equipment. In order to avoid damage to the filaments or bristles in this zone, it is advantageous to efiect the first stretching directly between the spinneret and a heated stretching roller or rollers, normally a pair of heated stretching rollers, whose speed of rotation and temperature correspond respectively to the desired stretching ratio and to the desired heat treatment. The duration of this heat treatment is regulaed by the number of turns described by the filaments or bristles around the said rollers, as well as by their dimensions and speed.

The temperature of the heat treatment is above 170 C. so as to ensure fairly extensive vulcanization of the diorganopolysiloxane, but below 320 C. so as to avoid degradation thereof. A suitable degree of vulcanization can be obtained either by using a high temperature for a short time or by using a lower temperature for a longer time. Preferably the heat treatment is carried out at a temperature of 210250 C. for less than seconds.

The second stretching and the winding-up can be carried out by means of any known device. The ratio of the second stretching must be between 1.2 and 4. The winding-up speed must be so chosen that the overall stretching ratio, that is to say the ratio of the linear speed at which the winding-up device is drived to the linear extrusion speed is between 1.2 and 4.

Thus in certain cases there may be a degree of spontaneous shrinkage between the second stretch and the winding-up. In order to facilitate the unwinding of the filaments or bristles and avoid sticking of the turns to one another on the package support, they may with advantage be given a second heat treatment between the second stretching and the winding-up, at a temperature which can be as high as 300 C., and for a period which can vary from a few seconds to a few minutes. This second heat treatment like the first, can advantageously be carried out directly on a roller or rollers, usually a pair of rollers heated to the desired temperature which also apply the stretching tension.

The process of the invention can thus be carried out using a device of simple and low-cost construction. It should in particular be noted that the extrusion of the diorganopolysiloxane composition is effected without using a spinning solvent, which is of great advantage both technically and economically, as against spinning processes starting from solutions of polymers, in which it is necessary to subject the filaments or bristles to various washes or other treatments to remove residual solvent, and thereafter to recover this solvent.

The filaments and bristles of the invention possess an essentially oriented structure which can easily be demonstrated by measuring their birefringence. Their mechanical and elastic characteristics are comparable to those of filaments and bristles based on natural rubber, and they retain these advantageous characteristics over a very wide range of temperatures from C. to 250 C. and even a little higher. They do not undergo any degradation during dyeing treatments carried out even above 100 C. Finally, their performance in use is excellent because they are remarkably resistant to light, even ultra-violet light, to atmospheric oxygen, to detergents and to perspiration.

The filament gauge of the filaments or bristles can vary within very wide limits depending on the extrusion conditions, from values equal to or below 75 dtex up to values equal to or above 2,000 dtex.

After winding up the filament or bristle on a support, it can in certain cases be advantageous to subject it to an oven treatment at temperatures which can range up to 200 C. for periods which can very from a few minutes to one day.

The invention is illustrated in the accompanying drawing which represents schematically a form of device that can be used in practicing the invention, and which will be referred to more particularly in Example 1.

The invention is also illustrated by the examples which follow, in which parts and percentages are by weight.

The following compositions are used in the examples: in Example 1,

Parts (1) A diorganopolysiloxane, of viscosity 250,000

poises at 25 C. and consisting of 99.77% of dimethylsiloxy units and 0.23% or methylvinylsiloxy units, the chain ends being blocked by trimethylsiloxy units (ii) Pyrogenic silica of high specific surface area,

treated with octamethylcyclotetrasiloxane (iii) A catalyst composition in the form of a paste,

obtained by mixing equal amounts of 2,4-dichlorobenzoyl peroxide and an u,w-bis(trimethy1siloxy(dimethylpolysiloxane oil, of viscosity 10 poises at 25 C. (iv) a plasticizer consisting of an a,w-dihydroxydimethylpolysiloxane oil of viscosity 0.4 poises at in Examples 26, the same constituents as in Example 1 but in the following proportions: a Parts (i) Diorganopolysiloxane d 1000 (ii) 'Pyrogenic silica 500 (iii) Catalyst composition 19 (iv) Plasticizer 13 in Example 7, the same constituents as in Example 1 but in the following proportions:

(i) diorganopoly siloxane of viscosity 500,000 poises at 25 C., and consisting of 87.0% of diffmethyls'iloxy units, 12.8% of diphenylsiloxy units f and '0.2 ofjmethylvinylsiloxy units, the chain ends being blocked by trimethylsiloxy units 1000 As'in Example 1 ii) Pygr ogenic silica 410 (iii) Catalyst composition 18 (iv) Plasticizer 25 n EX'amP eQ; f I

q Parts (i,)f'A diorganopolysiloxane .of viscosity 50,000 poisesat 25 C. and consisting of 99.77% of div methylsiloxy units and of 0.23% of methylvinylsiloxy units, the chain ends being blocked by dimethylvinylsiloxy units 1000 (ii) Pyrogenic silica of high specific surface area 510 (iii) Acatalyst composition in the form of a paste, obtainedby mixing equal quantities of 2,4-dichlo- .-robenzoyl peroxide and an a,w-bis(trimethylsi- .-loxy)dimethylpolysiloxane -oil of viscosity 0.4

poise at 25 C. 28

(iv) A plasticizer consisting of tetramethylethylenedioxy-dimethylsilane 17.5

(ii) Pyrogenic silica 'as- 'inExample 9 Parts (iii) A catalyst composition as in Example 1 30 (iv) Plasticizer as in Example 1 17.5 (v) Iron octoate as in Example 9 7.5 in Example 11,

Parts (i) A diorganopolysiloxane of viscosity 200,000

poises at 25 C., and consisting of 84.77% of dimethylsiloxy units, 15% of methylphenylsiloxy units and 0.23% of methylvinylsiloxy units, the chain ends being blocked by trimethylsilyl units (ii) Pyrogenic silica of specific surface area 300 m. g. 450 (iii) A catalyst composition as in Example 9 n 30 (iv) Plasticizer as in Example 9- 17.5 (v) Iron octoate as in Example 9 7.5

EXAMPLE 1 After working the composition specified above for this example in a two-roll mill, the homogeneous mixture obtainde is converted usin gthe device shown in the drawing. Referring to the drawing, the mixture is introduced into an extruder 1 from where it is passed by a metering pump 2 through a spinneret 3 which is pierced with a circular orifice of diameter 0.3 mm., at a linear extrusion speed of 7.8 m./minute. The resulting filament passes 3 times round rollers 4 and 5 of diameter 147 mm., which roate at a peripheral speed of 10 m./minute, giving the filament a first stretch at a ratio of 1.28. The rollers are at a temperature of 235 C., and the duration of contact of the filament with the rollers is about 8 seconds.

After having left the roller 5, the filament passes 5 times round rollers 6 and 7, also of diameter 147 mm., which rotate at a peripheral speed of 30 m./minute, giving the filament a second stretch at a ratio of 3. The rollers 6 and 7 are heated to a temperature of 235 C. so as to make the filament easier to unwind. The duration of contact of the filament with these rollers is about 5 seconds.

After leaving the roller 7, the filament is wound up on a support 8 at a linear speed of 30 m./minute. The overall stretch ratio of the filament, after winding up, is 3.8.

The filament thus obtained has a gauge of 650 dtex, an I elongation at break of 480%, and a kilometric breaking strength of 1.29, corresponding to a tenacity of 151 kg./cm.

EXAMPLES 2-11 The respective homogeneous mixtures obtained by working the relative compositions specified above for these examples are converted by means of the device and according to the process generally described in Example 1, variations in equipment and/or processing conditions being shown in the following Table I.

TABLE I Linear speed imparted Duration of Diameter to fila- Temperacontact 1st stretch of Linear ment by ture of filament] ratio imspineret speed of by rollers rollers rollers parted by orifice(s) extrusion 4 and 5 4 and 5 4 and 5 rollers (mm.) (an/min.) (In/min.) 0.) (secs) 4 and 5 See footnotes at end of table.

TABLE-Continued Linear speed imparted Duration of to fila- Temperacontact 2nd stretch ment by ture of lament! ratio im- Linear Overall rollers rollers rollers parted by winding up stretch 6 and 7 6 and 7 6 and 7 rollers Speed ratio after Ex. No. (m./min.) 0.) (secs.) 6 and 7 (m./min.) winding up 15 Unheated 1. 25 19 1. 90 30 235 -4 3. 33 26 2. 9 26 280 -3 3. 6 20 2. 5 l8. 5 100 -6 2. 17 15 2. 5 18. 5 285 -6 2. 17 15 2. 18. 280 -7 2. 2 17 2. 1 19 180 -9 3. 1 19 3. 8 10 200 M90 1 4 8. 5 1.6 10 195 -70 2 8 2. 2 11 10 195 -70 2 8 2. 2 1 Except for the device of Example 5 all spinerets have a single circular orifice; the spineret used in the device of Ex. 5 has three orifices of diameter 0.2 m

I The filament is keptin an oven at 200 C. for 24 hours after the winding up operation.

The following Table H shows the results obtained in terms of gauge, elongation at break, kilometric breaking strength and (for Examples 2-9) the corresponding tenacity.

While in this specification we have referred to both filaments and bristles, it will be understood that there is no sharp dividing line between the two. It is however conventional to use the term bristles, to denote filaments of sufiiciently high gauge to be relatively stiff, and this usage is intended here.

We claim:

1. A process for the production of filaments and bristles having a basis of a vulcanized diorganopolysiloxane, which have both a kilometric breaking strength greater than 1.25 and an elongation at break of at least 300%, which comprises extruding through a spinneret at an ordinary temperature a composition consisting essentially of 1,000 parts by weight of the unvulcanized diorganopolysiloxane of the formula:

specified above, and n is a number from 2,000 to 20,000, I

3001,000 parts by weight of a filler and 3-30 parts by weight of a vulcanization catalyst for the diorganopolysiloxane, stretching the resulting filaments or bristles at ambient temperature to cause a permanent elongation of up to 50% of their initial length, vulcanizing the fila- 3. A process according to claim 1, in which the fila-.

ments or bristiles are heated, and the tension required to effect the first stretch is applied to them, by a single device which comprises at least one heated roller around which they pass. 7

4. A process according to claim 1, in which after the second stretch and beforebeing wound up the filaments or bristles are heated to a temperature'up to 300 C.

5. A process according to claim 4, in which this second heating is effected by contact with at least one roller which imparts the tension required for the second stretch.

6. A process according to claim 1, in which the filaments or bristles are further heated at a temperature up to 200 C. while wound up on a support.

7. A process according'to claim 1, in which the un-, vulcanized diorganopolysiloxane hasa viscosityv at. 25 C. of 10,000-600,000 poises. v I 8. A process according to claim 1, in which a free radical-producing vulcanization catalyst is employed.

9. A process according to claim 1, in which the filler is silica of high specific surface area. 10. A process according to claim 1; in which the composition which is extruded contains also a plasticizer.

11. A process according to claim 9, in which the plasticizer is an organosilicon compound.

References Cited UNITED STATES PATENTS 2,059,284 11/1936 Schade 264-236 2,709,161 5/1955 Kilbourne et al 264-236 3,234,174 2/1966 Williams 260-37 SB 3,268,473 8/1966 Brown 260-37 SB 3,328,340 6/1967 Vaughn 260-37 SB 3,529,035 9/197-0 Lamoreaux 260-37 SB 3,677,784 7/1972 Natzsche et a1. 260-37 SB 3,340,228 9/1967 Wu 264-176 F JAY H.,WOO, Primary Examiner US. Cl. X.R.

26046'.5 R, 46.5 G; 264-176 F, 236, 290

UNITED STATES PATENT OFFICE 4 CERTIFICATE OF CORRECTION Patent No. 3, 781, 400 Dated December 25. 1973 Inventor(s) PAUL COUCHOUD et. al

It is certified that error appears in the aboveidentified-patent and that said Letters Patent are hereby corrected as shown below:

In the heading, the assignee should read:

- Rhone-Poulenc-Textile,

Paris, France Signed and Scaled this Twenty-fifth D ay of January 1977 [SEAL] Arrest:

RUTH C. MASON C. MARSHALL DANN ffi Commissioner oj'latenls and Trademarks UNITED STATES PA'iENT OFFICE Patent No. 3,781,400 Dated December 25, 1973 Inventor(s) AUL COUCHOUD et a1 It is certified that error appears in the above-identified patent and that said Letters Patentare hereby corrected as shown below:

In the heading,- please add the claim for Convention priority as follows:

-Claims priority, application France,

December 30, 1 968, No. 181,949 and October l4 ,.l969,-No. 69, 352l0.

Signed and' sealed this 15th day of August 197 (SEAL) Attest:

MCCOY M. GIBSON, JR. c. MARSHALL DANN Attesting Officer Commissioner of Patents 

